Project Schedule Development under Environment-Induced Time-Window Constraints: Case of Constructing River-Crossing Bridge in Remote Northern Region

Abstract

A review of literature and practice indicates that there has been a lack of academic research and that there is a shortage of appropriate methods for construction planning and project scheduling for development of projects in northern and remote regions. This study proposes a new project planning method that features seamless integration of specific time-window constraints due to seasonal cycles and environmental regulations. In contrast with the established critical path method, with the proposed method there is no need to estimate each activity’s duration up front as schedule inputs. Instead, a project plan is devised analytically, satisfying all time-window constraints imposed by the environment and precedence relationships defined by construction method. The resulting allowable duration of each activity is further confirmed through activity-level planning. A case study was conducted to schedule the construction of a river-crossing bridge situated at a remote location in the northern region of Canada. Two construction methods (namely crane erection versus incremental launching) were contrasted in two application scenarios. A third application scenario investigated the effect of adjusting the time-window constraint for berm installation activities in implementing the incremental launching method. A novel project scheduling method is proposed herein to assist practitioners in planning construction activities in northern and remote regions subject to limited accessibility, seasonal cycles, and harsh environmental conditions. Current mainstream project planning methods and tools (e.g., critical path method and Primavera P6) do not adequately factor in environment-induced constraints in scheduling analysis. Therefore, the resulting project milestones, duration, and budget, which often serve as contractual commitments and baselines to assess project performance, are almost certain to be overly optimistic and unrealistic. In the proposed new method, a planner needs to specify time-window constraints due to seasonal conditions and environmental regulations. A project schedule is analytically devised, satisfying all the time-window constraints imposed by the environment and precedence relationships defined by the construction method. A case study was conducted to schedule the construction of a river-crossing bridge situated at a remote location in the northern region of Canada. The construction method of crane erection was contrasted with incremental launching while holding all activity time-window constraints identical.